This invention relates to a brake pad for disc brakes having a damping plate fixed on the reverse face of a lining carrier plate, whereby the damping plate reduces braking noise and provides heat insulation.
It is known in the prior art that braking noises, in particular squealing, can be suppressed by fixing a damping plate to the reverse face of a lining carrier plate of a brake pad. The damping plate is also suited for heat insulation with respect to the hot brake pad of the piston of a hydraulic actuating apparatus being pressed against the reverse face of the lining carrier plate in order to protect the hydraulic fluid from overheating and forming bubbles. Such a damping plate is generally cemented to the reverse face of the lining carrier plate. This form of attachment, however, bears the disadvantage that the damping plate may twist or slip away in the event of heavy strains on the brake.
In a brake pad which is known from U.S. Pat. No. 4,846,312, an anti-twist protection is envisaged. The lining carrier plate is formed with holes which are engaged by correspondingly shaped sections of the damping plate. The damping plate is, however, still retained by cementing. The risk of falling out is not yet excluded in this invention. It is a further disadvantage that additional manufacturing cost is incurred for the configuration of the damping plate and of the lining carrier plate, as well as the cost of cementing.
It is known in the prior art to fix the damping plate to the lining carrier plate by riveting. The riveted couplings, however, have the disadvantage of being very rigid. It has become evident in practice that inaccuracies due to manufacturing techniques or to heat expansion of the damping plate and the lining carrier plate in a hot brake pad lead to buckling-up of the damping plate which then no longer planely abuts the lining carrier plate. This will in turn deteriorate the noise abating properties of the damping plate.
In view of the above-referenced problems associated with braking systems, some attempts have been made to remedy them. For example, EP 0224988 A1 teaches providing slots in the dampening plate so that when rigid rivets are used in the brake assembly, any mechanical stress which is developed is compensated for and damping plate buckling is prevented. Although this approach may be satisfactory in addressing the problems associated with damping plate buckling, this arrangement is not optimal regarding the rigidity and consistency of the damping plate and also regarding the manufacturing effort entailed.